Minoru Yamasaki was the architect of the World Trade Centre. A second-generation Japanese-American born in Seattle in 1912, he lived out the American dream on the biggest possible canvas - hundreds of thousands of tons of concrete, steel, brick and glass. From a poor background, he worked his way through college, at the University of Washington, making 17 cents an hour at a salmon cannery. He came to New York in the 1930s with $40 in his pocket and landed a job with Shreve, Lamb and Harmon, architects of the Empire State building. This was the tallest building in the world until the dedication of the twin towers of Yamasaki's World Trade Centre in 1973.

Yamasaki's great love as he grew older was for the sensual architecture of Moghul India - he adored the Taj Mahal - and the serenity of traditional Japanese design. For a man who built some of the world's most overtly commercial buildings, this might seem an aesthetic contradiction, particularly because in 1955, Yamasaki had built the Pruitt-Igoe Housing Project in St Louis. This was so unpopular that it was demolished, by official order, in 1975 prompting the influential American architectural critic and historian, Charles Jencks, to announce the death of Modernism. After the walls of Pruitt-Igoe came tumbling down, said Jencks, we entered the split-pedimented portals of the complex and contradictory world of postmodern architecture.

Yet, who could have been more complex and contradictory than Yamasaki? He loved the lightness and grace of traditional Japanese housing but built one of the most lumpen and hated of all social housing projects. "Man needs a serene architectural background to save his sanity in today's world," he said. He added: "Buildings should not awe and impress, but rather serve as a thoughtful background for the activities of contemporary man."And yet he designed those great unblinking steel and concrete sentinels looming - respected, but surely never loved - over Wall Street that were the target of Tuesday's unprecedented attack. He was also the architect of a number of coolly efficient international airport buildings from which the Boeing jets that would ultimately destroy his principal work, and so many lives, took off and landed.

Yamasaki chose to live in a decidedly low-rise home. No matter how beautifiul individual skyscrapers can be, many find them aggressive, obtrusive, wrong-headed and even frightening. The events of this week can only heighten their fears.

From 1941, Yamasaki married four times. In 1969 his fourth wife was also his first. It might be said that he had come full circle emotionally, just as, philosophically, he had returned by his death in 1986 ever closer to his oriental roots. When the question is raised, as it has been this week, as to whether the skyscraper has reached the end of its world-dominating cycle, we should pause and remember the life of Yamasaki. Here was a man who rose to the heights of his profession and who represents the immigrant's dream of graduating from col lege and succeeding in a profession, and, yet, under the skin - whether black, white, brown or yellow - still nurtures a quiet, small dream of something like a fishing hut with a palm-leaf roof loafing beside a warm, coral blue ocean or, perhaps, a house with paper screens set in an ornamental garden. These are low-key architectural expressions of a way of life close to nature and informed by older religions.

Yamasaki made it bigger than anyone else in New York. He endowed the city with these twin 1,360-ft towers, which acted, on the great stage of Manhattan, as a kind of giant anchor for a city whose greatness is built on transport, immigration, trade and reaching for the sky. That the city's principal buildings resemble outsized space rockets should be no surprise. From around the turn of the last century, in these machines for making money, New York lifted off into the heady heights of global capitalism, blasting its way through two world wars and the cold war. The skyscraper is such a symbol of American values and of New York in particular that no one could imagine it vanishing from the skyline, unless unwontedly and by terrorist action. The Manhattan skyscraper has seized the imagination of cities, councils and corporations worlwide. But the implosion of the twin towers of the World Trade Centre and all those thousands of lives, loves and aspirations crushed in them does not signal the beginning of some new era in architecture.

Yamasaki would have been surprised by the destruction of the World Trade Centre. Aaron Swirksy, one of his design team, expressed disbelief this week on hearing of the collapse of the twin towers. He told Jerusalem Post radio that the building had been designed with accidents in mind. "There was always the possibility of an accident with a plane hitting the building", he said. "Even a big hole in such a structure should leave it standing."

"It's not incredible," says Frank Duffy, a British architect specialising in office design and space planning based in New York. "We know that the engineers [John Skilling and Leslie Robertson] did think of accidents involving planes. Plans for the Boeing 747 were announced in 1965 and production confirmed the following year when work on the World Trade Centre began. What they don't seem to have counted on was the terrible heat generated by thousands of gallons of burning kerosene. Steel appears to have turned almost to butter. As the upper floors hit by the aircraft began to give way, they pressed with ever-growing weight on the floors below until the entire structures imploded."

Duffy, a witness to the destruction says: "Of course it's not the end of the skyscraper. You can't design an indestructible building, much less an indestructible city. Even if you did away with high-rise buildings and dispersed the city and knitted it together with the internet, its electronic intelligence, its money-making ability, could be destroyed by computer viruses. You don't need to kill people to undermine an economy, although you might want to for reasons of revenge and sheer terror."

The skyscraper as we know it - a highly serviced office or residential tower, and sometimes both - emerged in Chicago after the city was all but destroyed by the great fire of 1873, giving architects the opportunity to build afresh using all the latest construction techniques and materials. A combination of reliable steel-frame construction and Mr Otis's elevators, invented in the 1850s, enabled architects to build high above the great wheat plains of Illinois.

The handsome 15-floor Reliance building in Chicago's Loop (the central business area), now a svelte hotel, designed by Charles Attwood of Daniel Burnham's office is generally considered to be the first real skyscraper. Completed in 1895, it caught the imagination of architects, politicians, the business community and public alike, and particularly in New York. Manhattan took up the skyscraper with a determination to outdo Chicago in the 1890s.

The great Chicago architect Louis Sullivan said this new form of building, "Must be every inch a proud and soaring thing, rising in sheer exultation." The mood was almost religious. This made sense, for the precursors of the all-American skyscraper were surely the ziggurats and spiral minarets of Egypt, the Middle East and Meso-potamia, the princely and mercantile towers of Renaissance Europe (think of the lofty, prickly monuments of San Gimignano, of Bruges and Regensburg) and the sky-piercing spires of Ulm and Salisbury.

All these were designed either to connect humankind to the heavens or to raise Mammon up into the pantheon of the gods. Or for reasons of sheer vanity. Some, like the great Gothic spires, were lightning conductors earthing divine energy; others, like the stepped pyramids of Sumeria and Mexico raised priests up to an eye level with God or the gods. All of them - those of the ancient, medieval and renaissance worlds - could be seen by the people they served, or subdued, for miles across rooftops, fields and pastures.

According to religious lore, God (in various guises) had his revenge on those who aspired too high. He poured confusion and misunderstanding on those who dared build the Tower of Babel (Genesis 11: 1-9), which was probably inspired by the spiral ziggurat of Etemenanki in Babylon. Babylon was in what is Iraq today.

Norman Foster, the globally acclaimed architect, landed in "the mother of all storms" at JFK airport the night before the attack on the World Trade Centre. He had come to discuss his design for a new skyscraper, the Hearst Tower planned for a site on Eighth Avenue in mid-town Manhattan. His meeting was cancelled, although the tower may yet be built. "Skyscrapers are as much a reality as urbanisation itself," says Foster. "They're not going to go away. There's no way society, much less architects, can design for the level of extremity we witnessed this week. Airliners are flying bombs in the wrong hands, and they're getting ever bigger."

On July 25, 1945, a twin-engined US air force B-25 Mitchell bomber flew, accidentally, into the north side of the Empire State building. Visibility was poor. Thirteen people died, mostly in fires caused by burning gasoline. True, the Empire State is a particularly tough structure, and the B-25 was at least 10 times lighter than the 767s that rammed into the World Trade Centre and, size for size, carried much less fuel. The modern aircraft were nothing less than piloted inter-continental ballistic missiles. Perhaps the dressed stone and rubble mass of that ancient skyscraper, the Great Pyramid of Cheops might have withstood these impacts better than Yamasaki's hollow office towers, but few other buildings through history could have.

"What do we do if we don't build high?", asks Foster. "Give up and live in bunkers? And then what, fret about the possibility of death by nerve gas or germ warfare? Do we stop sailing when a ship sinks or give up on metro systems if a terrorist plants a bomb? Architects and engineers learn from feedback, by experience, and there will be several lessons to learned from this week's tragic events.

"Yes, we can design to counteract forces of nature to some degree, but earthquakes can take out entire cities and, in the great scheme of things, there's nothing you can do short of moving cities on seismic faults elsewhere. Should we be designing groundscrapers instead of skyscrapers? A determined terrorist could crash-land one of the next generation of super-Jumbos across a suburban sprawl and kill thousands."

Building high has never been a simple case of hubris. Ever-rising land prices encourage us to reach, however unpredictably, further upwards. In the case of New York, Hong Kong or Tokyo, there is only a given amount of land to build on. Just as steam rises through the safety valves of a boiler at a certain pressure, so eventually city buildings must begin their ascent above the classical skyline. But, anticipating earthquake, fire or terrorist attack, should we be thinking of dispersing commercial centres?

"No", says Richard Rogers, urbanist and architect of the Lloyd's building in the City of London, workplace of those charged with the commercial nightmare of arranging insurance payouts in the wake of last Tuesday's attack. "People like to gather. You can have all the electronic communications technology you could ever want but miss the city. New York is a wonderfully exciting and vibrant place for many reasons, but one of the key reasons is its density, the fact that so many people from different cultures and parts of the world come together here. Such density has led to great achievements in the arts, to fusions and crossovers in culture, music, fashion, language, literature." And, of course, architecture. "We can expect to build higher still."

How high? In the approach to the Millennium, Foster and Partners proposed a 2,500-ft tower designed for a working and residential population of at least 55,000, 5,000 more than that of Yamasaki's twin towers. Frank Lloyd Wright, the American architect, had already gone one better shortly after the second world war when American values were at their zenith, with his design for the Illinois, a mile-high skyscraper, twice as high as Foster's.

How would you have got to the top? By nuclear-powered lifts. Could it have been built? "Sure," says William Baker of the giant US architectural and engineering practice Skidmore, Owings and Merrill and engineer of the world's tallest building, the Petronas Towers in Kuala Lumpur. The sky's the limit, according to Baker, engineer in charge of the structural design of 7 South Dearborn in Chicago, at 2,000 feet - including its twin digital communications antennae - the world's next tallest building. "The word skyscraper," says Baker, "derives from the topmost sail of a ship, and this new building is effectively a very tall mast with the floors cantilevered out from it. It aims to be very graceful and very light for a building on this scale."

Theoretically, it could be extended thousands of feet above lake Chicago. Baker and his colleagues don't see 7 South Dearborn as a target for terrorists. A tower mixing homes, offices for young businesses, restaurants and shops, it is not intended to be a symbol of the might of global capitalism, but of the sheer brio and renewed self-confidence of the city of Chicago. And if someone chose to destroy it, it could, like the campanile of St Mark's in Venice, which collapsed in 1902, be put up again.

No. The skyscraper, unless we choose to spread ourselves infinitely across the landscape or take to bunkers, is here to stay for a long while yet. Can we make it safer? "What we might learn as architects," says Richard Rogers, "is to take a fresh look at the issues of fire and safety. We need to ask questions like, could more people have escaped before the towers collapsed?" Or, as Cecil Balmond, co-designer of the Victoria and Albert museum's long-awaited Spiral gallery and one of today's most original structural engineers, asks, "could we include safe havens in tall buildings, zones that are, as far as possible fire-proof and crush-proof? Maybe, but nothing can stop guided missiles and that's what those 767s were."

Balmond argues, although he knows that this is less than scant comfort for those killed or bereaved in New York this week, that Yamasaki and his engineers got something right. "The towers imploded. If they had toppled, they would have crashed across other buildings and streets and many more thousands of lives would have been lost. It is impossible, though, to imagine the heat generated by all those thousands of gallons of kerosene ablaze in the damaged buildings. In such extreme circumstances the towers probably did well to stand for as long as they did."

But, what about those who jumped to their deaths? Was there nothing else they could have done? What about issuing those who live and work in skyscrapers with parachutes? Surprisingly neither Foster nor Rogers, Baker nor Balmond find this suggestion absurd. Why not? We provide our city embankments with lifebelts. They have saved many lives. It's a thought anyway. Can you think of anything better, short of not building high? But Balmond acknowleges it wouldn't be so easy. "People could be thrown back against buildings and the logistics would be difficult," he says. "Just maybe, it could be worth a try." The idea, however, can only make those who fear skyscrapers more nervous still.

But for many, until this week's tragedy at least, there is something thrilling about living and working high in the sky. Recently I visited Lynn Osmond, president of the Chicago Architecture Foundation. Her home is an apartment on the 45th floor of a downtown tower overlooking lake Michigan on one side and Big John, the 100-floor John Hancock Centre, on the other.

She spoke of the sense of awe she feels during thunderous electric storms when jagged forks of lightning stab into the twin red-and-white communications antennae that rise 350 ft above the hugely popular 95th floor Signature room cocktail bar of Big John. She is fascinated by the days when her skycraping home becomes a cloudscraper and the views vanish altogether as if a vast pair of grey curtains were being drawn across the armoured glass windows. And there are those days when the streets and sidewalks below are hidden by cloud, yet the sky outside her window is azure blue tinged with gold.

The skyscraper has long emigrated from Chicago and New York to the countries that sent America their poor, huddled masses, people aiming to build a new life like Minoru Yamasaki's parents, welcomed successively by the Statue of Liberty, the 792-ft Woolworth building, from 1913, and, from 1973, the twin towers of the World Trade Centre. Skyscrapers in the pipeline much higher than Yamasaki's include the Shanghai World Financial Centre (1,509 ft) and the Centre of India Tower, Katangi (2,222 ft).

"Building high is a human aspiration", says Cecil Balmond. "We will continue to do it. Sadly, but truly, engineers learn from error, disaster and tragedy. Each time, we try to make the world a safer and better place. But, no building, from a Japanese tea pavilion to the tallest skyscraper can be immune from those determined, for whatever reason, to destroy and kill."